Malaria is one of the most deadly diseases affecting third world countries, and claims more than a million lives annually. While various classes of antimalarial agents are available, chloroquine remains the main stay of therapy against malaria. Increasing resistance of Plasmodium falciparum, the most dangerous of the four malaria parasites that infect humans, to common drugs such as chloroquine has heightened concern about malaria. Extensive programs are underway to screen natural products and synthetic derivatives for new agents. Against this background, isolation of artemisinin as the active principle of Chinese herb Artemisia annua has opened new possibilities in malaria chemotherapy.

Semisynthetic derivatives of artemisinin such as arteether, artemether and artesunic acid, are currently the drugs of choice for the treatment of complicated cases of malaria such as cerebral malaria [For reviews on artemisinin and its analogues see; (a) Klayman, D. L. Science 1985, 228, 1049. (b) Bhattacharya, A. K.; Sharma, R. P. Heterocycles 1999, 51, 1681. (c) Borstnik, K.; Paik, I.; Shapiro, T. A.; Posner, G. H. Int. J. Parasitol. 2002, 32, 1661. (d) Ploypradith, P. Acta Trop. 2004, 89, 329. (e) O'Neill, P. M.; Posner, G. H. J. Med. Chem. 2004, 47, 2945]. The limited availability of artemisinin from natural sources and the fact that endoperoxide linkage present in form of a 1,2,4-trioxane ring system is the antimalarial pharmacophore of these compounds, has led to the present effort to develop structurally simple synthetic trioxanes. Several structurally simple synthetic 1,2,4-trioxanes have shown promising antimalarial activity [(a) Bhattacharya, A. K.; Sharma, R. P. Heterocycles 1999, 51, 1681. (b) Borstnik, K.; Paik, L.; Shapiro, T. A.; Posner, G. H. Int. J. Parasitol. 2002, 32, 1661. (c) Singh, C.; Misra, D.; Saxena, G.; Chandra, S. Bioorg. Med. Chem. Lett. 1995, 5, 1913. (d) Singh, C.; Puri, S. K. U.S. Pat. No. 6,316,493 B1, 2001. (e) Singh, C.; Gupta, N.; Puri, S. K. Bioorg. Med. Chem. Lett. 2003, 13, 3445. (f) Singh, C.; Tiwari, P.; Puri, S. K. PCT patent application No. PCT/1N02/00093, dated 28, Mar. 2002]. Singh et al. have developed a novel photooxygenation route for preparation of 1,2,4-trioxanes. β-Hydroxyhydroperoxide prepared by regiospecific photooxygenation of allylic alcohols on condensation with aldehydes or ketone in presence of acid catalyst furnish 1,2,4-trioxane. [(a) Singh, C.; Misra, D.; Saxena, G.; Chandra, S. Bioorg. Med. Chem. Lett. 1992, 2, 497. (b) Singh, C.; Misra, D.; Saxena, G.; Chandra, S. Bioorg. Med. Chem. Lett. 1995, 5, 1913. (c) Singh, C.; Puri, S. K. U.S. Pat. No. 6,316,493 B1, 2001. (d) Singh, C.; Gupta, N.; Puri, S. K. Bioorg. Med. Chem. Lett. 2002, 12, 1913. (e) Singh, C.; Gupta, N.; Puri, S. K. Bioorg. Med. Chem. Lett. 2003, 13, 3445. (f) Singh, C.; Tiwari, P.; Puri, S. K. PCT patent application No. PCT/1N02/00093 dated 28, Mar. 2002]. This method has been extended to prepare several amino functionalized 1,2,4-trioxanes, some of which have shown moderate antimalarial activity against multidrug resistant P. yoelii in mice [Singh, C.; Malik, H.; Puri, S. K. Bioorg. Med. Chem. Lett. 2004, 14, 459]. It is desirable to develop new compounds with show high degrees of anti-malarial activity in order to overcome the problems associated with the prior art compounds including the problem of drug-resistance in the malarial virus.